Gauge



April 17, 192s. 1,666,556

A. o. cRAVlN Filed Dec. 29, 1925 -4 sheets-sheet 2 f f l l l l 4,

I Zi/ZUM@ @Wam 0, 866,6@

April 17, 1928.

A. O. CRAVIN GAUGE Filed Dec. 29, 1925 4 Sheets-Sheet 4 Patented Apr. 17, 19?..8.`

UNITED kAustern o. oRAvIN, oF cureneoyntmors.

l GAUGE.

Application ied December 2e, 19u25'. A :serian No. l78,683.

The principal object of my invention v to provide a gauge operatedby pressure kor vacuum or 'otherwise that is more reliable than4 any prior gauge, that will continue to register correctly fora very long period rand that will not require frequent testing and repairing.

Other objects malte a more sensitivefgauge.

Still other objects Will be pointed outY below. Y y

A feature of my gauge is the absence of a huir spring heretofore used to take up the slack motion 'of some ofthe connecting parts. l

Another feature is `a pivotal connection which includes a -lnife blade edge.

Another feature is a one-link connection between the Bourdon tube and the sector. i

ln the accompanying drawings:

Figure 1'is a. front view of a pressure gauge eonstructedin accordancegwith my invention andfshowi'ng'on'e form 'of the latter.

Figure is an enlarged detail of a portion of one of the spring connectors .and the abutment member engaged by it. y

Figure 3 is' a sectional detail of the terminal forming part of the free end ofthe Bourdon' springtube of the gauge shown in Final' Figure Llis a sectional adjusting abutmenty screivher'einafter .described;v Y y y Figureb is an enlarged section on line 5 of Fig. 1, omit-ting thecasingo'r hous- Figure: 6 is an enlarged detail of the Ahub portion of the sector ofthev gauge shown in Fie'. 1 and some of the adjacent parts.

F iuure' illustrates another formof sector and fulcrum post. f v

vFigure 8 is a frontviewv of another form of pressure 'gauge embodying iny invention..

Figure 9 is an enlargeddetail illustrating the construction of the hub portion'of fthe sector shownin Fig. 8, and o f the ful'crum pillarfor said sector. K VFigure 10 is an el vationof one ofthe spring connectors shown in Figi 8'..

Figure V11 is a'nelevat'ion oif the freev end shown in Fig. '8L y l 1 y Figure 12 is ausecrtion Online 12j- "12-of portion' of one of the Bourdon springftubes Fig'. 8` vbut with( casing or housing;

omitted.

are tov reduce friction andto from-the hub of a sector 15.

Vdetail of the tube Figi'ire lfis a plan vie'vv, enlarged, of. a modified forin ofinovement for the type of gauge shown F ig. 8. i

Having referenceto igs. l'to 7,'inclusive, 1 represents the body portion of the usual housing yof my improved pressure gauge. v Within this housing' 1s a socket 2secured thereto by screws Spandhaving athreaded extension 1 extendingV through the Wall'of the housing to the exteriorrof the latter, as usual.A Socket 2 `has secured to its one end of a Bourdonv spring tubey 5 Whose free end equippedvivith a terminal 6, Figs. 1 and 3, formed with a slot 7 Within which the shank ond portieri of aslieet metal spring connector' blade 8 is.l fastened, with pror uis/.ion `for us'tmentLby means of ascrevv 9. The opposite' end port-ion of connector 8 is bent to provideE a transverse groove 10 and y a lip or lblade 11,'as shown particularly in F ius. 2 and 6. The groove 10 is occupied by a knife-blade 12 provideduponlan abutmentmember 133'. the' latter being formed 'vvith `a threaded lile through it', and being 'screuied on toa ythreaded stem 14 projecting. y n y This hiiibfof sector7'15 includes vasv a rigid part thereof. a sheet metal tube-16 which is substantially 'elliptical ineros's-sectio'n and is driven into a correspondingly shaped hole formed in the hubp'ortziou of sector .15.* Upon its interior the `tube v16 i's 1nade' with a knifeiblade 17 extending'longitudnallv from end `to end thereof, and thislrniferblade is seated Within av groove 18 .formed Vlongitudinally upon oney side of a pillar or' fulcrum vpost 19, and always is] heldthereiu by l the pressure of the spring connect-or8...A "At its lovve'rv end the fulcrlim lpost/V19 is permanently secured to ak plate 20' \vhi`ch',l in turn;` is secured tothe housingv 1 byscrews 21. The tube 16 rests at its loiver end upou the plate 2O and is held? against y man1 ard 'n displacement; lvvitho'ut interference vwith` rotaryV movement thereof, 'afnut 22 screwed upon the upperreduced and threaded-end portion of the' fulcrum llieteeth of thesector 15, 'at the free end ico o f the' latter mesh with a piiio'rfZQA provid# theforin 'of a screw ,occupying a threaded .hole in' the base' plate 2Ok andserves also Vto clamp" ahollow post 26 securely t'osaid 'base ing for the greater part of the hand arbor and for its pinion Q2, being formed with an opening through its side as at 27 to permitof engagement of the sector with the pinion. As will be clear from Fig. 6 the interior of the sleeve lo is greater in size thanl the fulcrum post 19 so that the only place of engagement between the two is between the knife blade 17 ot' the sleeve and the bottom of the groove 18, sufficient clearance being providedat each side of the post, as at 28 and 2S), to allow the sector to swing to the limit of its movement-is either direction uithout interference between the sleeve 16 and the post. Also sufficientclearanee is provided between the sleeve and post at. the side of the latter opposite knife blade 17, as shown at 30. to avoid` rubbing engagement between the sleeve and post. 1

.-llrdjustably mounted ina threaded hole provided through the annular' wall of the housingv l (Fig re l) is an abutment screw 3l which bears against the outer side of the Bourdon spring tube 5 at a point close to the anchored or hxed end ot' the latter. By adjusting screw 3l the tube 5 may be flexed or shifted in either direction to set or reset the hand of the gauge, the resulting` adjustynient of the free end oil tube 5 acting' throught-he spring connector 8, sector' 15 and pinion 22 to shift the hand when this adjustment is made.

ln order to lock the screw 31 in adjusted position andpre'vent accidental displacementthereof, said screw is split as shown at 32, Fig. Il, and sprung outwardly so as to frictionally grip the Wall of the threaded hole occupied by it. .Also, vthe screw 31 is preferably made in the form of a thinrble with its open end'outermost and is provided near the inner end of its interior with a cross-bar 33 for engagement with a special tool or wrench by n'leans of which the screw is operated. i

In Fig. 7 I have` shown a modified :torni of movement. wherein the fulcruin knife blade li'f is formed yupona rod 1G driven into a. pocket 3d formed through the hub portion of the sector 15'; This pocket 34- opens into a hole 35 formed through the hub ot the sector for the l-ulrruin post 19. Like the sleeve 16, the rod 16 is made of a length to extendupwardly to the nut 22, Fig.V 5, and downwardly to the base plate 20, so that the rsector is supported thereby at the proper height.

The gauge above described dispenses with the use of a delicate vhair spring such as heretofore employed'to take up the slack motionin the joints in order'to effect atrue indication ofpressure, as thepressure of the springconnector 8 is ina direction to force all bearings together and to hold the sector in lposition relatively to the pinion so that there is no slack or lost. motion either between the sector and its pinion; between the sector and its fulcrum post or between the sector and the freeend of the lBourdon spring tube 5. The elimination of the hair spring referred to reduces the friction on the hand arbor bearings and cogs. Further'- inore, the construction described provides a gauge that is very sensitive, has a steady hand, and one that will register correctly on low pressures without. the presence of drag. A gunimy condition ofthe lubricant i* the joints of gauges as heretofore construch ed, or the presence of dust and dirt in certain places, may cause the hand to stick or dra-g, thus causing incorrectreading. rthis is impossible with my improved gauge as it is impossible for dust and vdirt to lodge between the knife blades andtheir seats and a gummy condition of the lubricant, if used, will knot interfere with the movement of the knife blades.

The screw 9 (Figure permits of adjustment of the length of the connector 8 to accord with the relation of the free end of the Bourdon tube with the movement.V Since the abutment member 13 (Figure 5) is free to adjust itself rotatively on the steinlll it is therefore free to lit itself exactly parallel to the groove l0 of the connector S whatever be the position of the latter. `Furthermore, by screwing the almtment member l?) toward or from the hub of the sector the throw of the hand, for a given movement of the tube 5, may be regulated or varied.

rlhe construction illustrated inFig. 7 is particularly adapted to those gauges where the movement extends downwardly from the hand arbor in which situation the fulcrum groove upon the post faces downward so that dust and dirtl cannot lodge therein.

lnconnection with this form, as.illustrated,l

3G provided upon j Til ies

l lt) la, said .socket being n'iadev with a threaded i y extension ll extending through said wall to the'exterior thereof.

.The movement" of this base plate l2 fastened by screwsl to 'the ,bottom of the housing l'aand to this base Y plate is fastened thelower'endvof a fulcruin postll, formed along one side thereofwith a groovet. ,Figsf andd12in which .is

seated ay knife blade 46 provided uponthe interior of ai sheet `metall sleeve fr?. Sleeve .ti'is driven into a hole formed through the huh of a sector whose teeth mesh wth v Y 12o Vgauge includes a v those of a pinion 49 on a hand arbor V50. The arbor 50 is disposed within a hollow post 5l xed at one end tothe basey plate 42 and has its inner end journaled in a bearing 52 while its opposite endportion is rotatably supported by aibushing 53 scri-wedl into the outer end of the hollow post. The post 5l is made with a side opening 54 through which the sector extends to engage the pinion 49. Theouter end of the fulcrum post 44 is reduced and threaded to receive upon it a nut 55, and the sleeve 47 is made of a length to extend from said nut to the base plate 42 so that the sector is thereby supported in proper position with relation to the pinion 49.

Pivoted at 56 to the sector near its vfree end isa floating equalizing lever 57. which lays alongside of, butA out of contact with, the sector, and this lever 57 is made with a hub portion y58 extending around the vhub of the sector with considerable clearance space o between the two. vHub 58 lof lever V57 is made with two oppositelydisposed substantially radial arms vhereinA shown as two threaded stems 59 and 60. Upon the stem 59 is adj ustably mounted an abutment member 6l formed with a groove 62 which provides a knife edge 63 atthe out-er side of the groove seated within Va groove provided at one end of a spring connector blade 64, said connector blade being yieldingly pressed against the abutment lmember 63. The shank portion of connector 64 occupies a position within a vslot 65, Fig. Vll, formed in a terminal 66 secured to the free .end of the tube 87, and is securelyrclamped therein with provision fory adjustment by ymeans of a screw 67 The abutment memberV 6l kis formed at its middle with a threaded hole to receive the'stem 59 and byrotation thereof its position with relation to the fulcrum blade 46 may be varied, V

The stem 60 alsol has an abutment member 68 mounted thereon formed with a groove 69 which provides a knife edge at the outer side thereof which yis seated within a. groove provided at thefree end of a spring connector' blade 71. The shank portion of connector blade 71 occupies a position within a slot 72 provided in a terminal 73 secured to the free end of tube 38, and is adjustably clamped insaid slot by means of a screw 74. The abutment member 68 made with an Unthreaded hole through it to receive the stem 60 and is held in position on the stem with provision foradjustment toward and from the fulcrum knife blade 46 by a nut 5. This method of connecting the abutment member 68 with its stem is resorted to for the reason that said member occupies a position so close to the sector 48 that it'can not be rotatedV for the purpose of adjusting it as in the case of theabutinent member 6l. Figure 10 is a side elevation of one of the spring connectors showing thev knife blade at one end thereof and each abutment member is of about the same length as its knife blade.

The floating vcompensating or equalizing lever '57, connected-as described with the two tubes, is provided-for the reason that said twotubes may not, and usually Ydo not, er;- hibit the same characteristics under variations of pressure, and inaccurate-indication would be the result of directly connecting the ytubes with the sector through one tube opposing the other at times. lVith the construction described the lever 57`11eutralizes the differing actions of the two tubes under variations of pressure since the hubportion thereof is free to shift laterally and centralize itself with respect to the two tube ends. Furthermore, thisfreedom ofself adjustment of said hub. portion prevents disengagement of the spring blades from the members 6l `and 68. i

'A double spring tube gauge constructed and operating as described operates with much less drag than double tube gauges ask heretofore constructed and is more sensitive on very low pressures than the single spring tube form. i

Figure 13 shows a modified form of movement for the double spring tube gauge, this lform kof movement being substantially the same as that already described except that it is constructed so that normally the axis of hand arbor 50,-pivot 56, knife blade 70, fulcruniknife blade 46 and knife blade 63,'are in alinement, which is a somewhat better `disposition ofparts than in Fig. 8. i

Among the advantagesv of my gauge I may point voutthat the knife'fbladespbeing slightly rounded at their edges, rock in their grooves with practically no friction; that the connectors, such as 8 (Figure 8), are clamped Vat their edges, and that the small clearance, as at 30 (Figure G), prevents blade y17A from slipping out of groove 18 wlienfthe connectorblade, such as 8, isl

released."

W hat l' claim is: I l.. A gauge comprising a sector ,a member rotatablyA and adjustably mounted on said sector. the axis of rotation of said member extending substantially l.riu'lially Vwith reference to the pivot ofv the sectorpresilient means operatively connected with said Bourdon spring and operatively connected with said adjustable member.

2. In a gauge the combination of a sector member` and'a fulcrum post member therefor, one of said members being formed with a groove and the other with a knife blade seated within said groove. j

3. In a gauge the combination of la sector member and a fulcrum post member therefor, one of said members being formed with a groove and the other with a knife blade Uil lll)

sea Within said groove; means for holding' said knife blade Within said groove With provision for swinging movement of said sector.

4. In a gauge the combination of a sector member Vand a ulcrum post member therefor; one of said members beingformed with a groove and the. other with a knife blade seated Within said groove; means for yieldingly holding said knife blade Within said groove with provision for swinging movement of said sector. y y

5. A gauge comprising a sector; a member threaded on; and adjustable longitudinally of; the sector; a Bourdon tube; and a spring` member directly connecting said Bourdon tube and said adjustable member and havc ing a resilient pivotal connection With one oit them.

6. A gauge comprising a Bourdon tube; a sector; a. member mounted on, and adj ustable longitudinally voi, thev sector; and a spring member directly connected to the Bourdon tube and having` an operative connection with said adjustable member consisting ot' a knife blade on one of said members and a cooperating` groove on the other.

7. A gauge comprising a Bourdon tube; a sector; a member mounted on, and rotatably adjustable longitudinallj,7 of; the sector; and a spring member directly connected to the Bourdon tube and having an operative connection with said adjustable member consisting` et a knife blade on one of said mem-v bers and a coopera-ting groove on the other.

8. A gauge comprisinga Bourdon tube spring;- having a terminal vvith a. slot; a sector; a resilient plate operatively connected to the sector and having a portion Within said slot; and means engaging the edge oit the plate to hold it adjustably in the desired fixed relation to the Bourdon spring.

y 9. A gauge comprising a sector; a member adjustably mounted on said sector; and movable radially o'f the sector 'for such adjust.- mcnt; a Bourdon tube spring; and resilientineans operatively connecting the spring' and adjustable member and having a. resilient pivotal. connection with one ol them.

10. A gauge comprising' a Bourdon tube spring; a sector; a resilient member operatively connecting' the sector and Bourdon spring and having` a resilient pivotal connection with one. of them; and means to adjustably hold the resilient member in the recense desired iixed relation to the other of said sector and spring.

1l. A gauge comprising a Bourdon tube spring; a sector; a resilient plate operatively connected to said tube spring and to said sector; and means engaging the edge of said plate to hold it in the desired lined relation to said spring or sector, said means being movable to permit adjustment ot thepla-te.

12. In a gauge the combination of a fulcrum post having a groove; and a sector member having knife blade seated Within said groove. y

13. A gauge comprising a Bourdon tube spring; a sector; a resilient member operatively connecting` the spring and sector to actuate the latter when the pressure increases and when the pressure decreases,y the connection of said resilient member Wit-h either the sector or tube spring consisting ot a kniie blade and cooperating groove; said knife blade extending, and the groove tacino, in a direction Which is substantially.

radial with reference to the pivot ofV the sector. v

14. A gauge comprising a Bourdon tube spring; a sector; and a member connected with the Bourdon spring Vand having a knitey blade to operatively vengage said sector to actuate the `latter Vwhen the pressureY in-4 creases` and when the pressure decreases; said knite blade extending in a direction which is substantially radial with reference to the.

pivot of the sector.v

l5. A gauge comprisingaBourdon tube spring; a sector provided'vvith a groove, the latter facing in a direction which is substantially radial with reference to the pivot of the sector; and a resilient member connected with the Bourdon spring` andl havinga knife blade edge to ride in said groove and actuate said sector when the pressure increases and ivhen the pressure decreases., f i6. A gauge comprising a Bourdon tube spring' ;l a sector member; and a member connected With the Bourdon spring; bers having an operative connection consisting of a knife blade on one .of them and a cooperatingV groove on thel other-to actuate the sector when the pressure increases and when the pressure decreases, the knife. blade extending. and the groove facinL reetion which is substantially radial with reference to the pivot of the sector.

AUSTIN o. oni-ivm.

g. 1n a d1-A 10e said mem- 

